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sphinx: Using hop_data to serialize per-hop information into onion

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Signed-off-by: Christian Decker <decker.christian@gmail.com>
This commit is contained in:
Christian Decker
2017-04-08 12:16:56 -07:00
parent 752f884c23
commit 83e89f0fe5
3 changed files with 68 additions and 23 deletions
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34
lightningd/sphinx.h
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@@ -9,11 +9,12 @@
#include <ccan/tal/tal.h>
#include <secp256k1.h>
#include <sodium/randombytes.h>
#include <wire/wire.h>
#define SECURITY_PARAMETER 20
#define NUM_MAX_HOPS 20
#define HOP_DATA_SIZE 40
#define ROUTING_INFO_SIZE (HOP_DATA_SIZE * SECURITY_PARAMETER)
#define HOP_DATA_SIZE 53
#define ROUTING_INFO_SIZE (HOP_DATA_SIZE * NUM_MAX_HOPS)
#define TOTAL_PACKET_SIZE (1 + 33 + SECURITY_PARAMETER + ROUTING_INFO_SIZE)
struct onionpacket {
@@ -34,23 +35,35 @@ enum route_next_case {
/* BOLT #4:
*
* The format of the per-hop-payload for a version 0 packet is as follows:
* The hops_data field is a structure that holds obfuscated versions of the next hop's address, transfer information and the associated HMAC. It is 1060 bytes long, and has the following structure:
```
+----------------+--------------------------+-------------------------------+--------------------------------------------+
| realm (1 byte) | amt_to_forward (8 bytes) | outgoing_cltv_value (4 bytes) | unused_with_v0_version_on_header (7 bytes) |
+----------------+--------------------------+-------------------------------+--------------------------------------------+
+-----------+-------------+----------+-----------+-------------+----------+-----------+
| n_1 realm | n_1 per-hop | n_1 HMAC | n_2 realm | n_2 per-hop | n_2 HMAC | ...filler |
+-----------+-------------+----------+----------+--------------+----------+------------+
```
The realm byte determines the format of the per-hop; so far only realm 0 is defined, and for that, the per-hop format is:
```
+----------------------+--------------------------+-------------------------------+--------------------+
| channel_id (8 bytes) | amt_to_forward (4 bytes) | outgoing_cltv_value (4 bytes) | padding (16 bytes) |
+----------------------+--------------------------+-------------------------------+--------------------+
```
*/
struct hoppayload {
struct hop_data {
u8 realm;
u64 amt_to_forward;
u32 outgoing_cltv_value;
u8 unused_with_v0_version_on_header[7];
struct short_channel_id channel_id;
u32 amt_forward;
u32 outgoing_cltv;
/* Padding omitted, will be zeroed */
u8 hmac[SECURITY_PARAMETER];
};
struct route_step {
enum route_next_case nextcase;
struct onionpacket *next;
struct hop_data hop_data;
};
/**
@@ -69,6 +82,7 @@ struct route_step {
struct onionpacket *create_onionpacket(
const tal_t * ctx,
struct pubkey path[],
struct hop_data hops_data[],
const u8 * sessionkey,
const u8 *assocdata,
const size_t assocdatalen